Plant Cell Chemistry PDF

CHEMISTRY AND ITS FUNCTION TO PLANTS  The living substance of cells consists of CYTOPLASM and the structures within it. About 96% of cytoplasm and its included structures is composed of: the elements carbon, hydrogen, oxygen, and nitrogen; 3% consists of phosphorus, potassium, and sulfur. T...

CHEMISTRY AND ITS FUNCTION TO PLANTS  The living substance of cells consists of CYTOPLASM and the structures within it. About 96% of cytoplasm and its included structures is composed of: the elements carbon, hydrogen, oxygen, and nitrogen; 3% consists of phosphorus, potassium, and sulfur. The remaining 1% includes calcium, iron, magnesium, sodium, chlorine, copper, manganese, cobalt, zinc, and minute quantities of other elements.  The large molecules invariably have “backbones” of carbon atoms within them and are said to be organic. The myriad of chemical reactions of living organisms is based on organic compounds. Most other molecules that contain no carbon atoms are called inorganic: Exceptions include carbon dioxide (CO2) and sodium bicarbonate (NaHCO3). The name “organic” was given to most of the chemicals of living things when it was believed that only living organisms could produce molecules containing carbon. MONOMERS AND POLYMERS Most cell components are composed of large molecules called macromolecules, or polymers (“many units”). Polymers are formed when two or more small units called monomers (“single units”) bond together. Four of the most important classes of polymers found in cells are carbohydrates, lipids, proteins, and nucleic acids. Chemistry of Life I. Inorganic Compounds Water II. Organic Compounds Carbohydrates Lipids/Fats Proteins Nucleic acid Characteristics of Water Water makes up 90% of the mass of most plants. Cohesiveness High heat of vaporization Versatility as a solvent Carbohydrates -Are the most abundant compounds. -C,H,O (1:2:1) Types of Carbohydrates Monosaccharides Simplest sugar (1 sugar unit) E.g. glucose/dextrose (blood sugar, physiologic sugar); xylose/ wood sugar (corn cobs); fructose/levulose/fruit sugar  2. Disaccharides - Composed of two monosaccharide units (2 sugar unit) - E.g. sucrose/table/sugar (glucose+fructose); trehalose (glucose+glucose); maltose/malt sugar/beer sugar (glucose+glucose); lactose/milk sugar (glucose+galactose) Types of Carbohydrates  3. Polysaccharides - Complex/ many sugar units (more than 10 sugar unit) - E.g. starch (plants); glycogen (animals); chitin (insects); cellulose (plant cell wall) Types of Carbohydrates  3. Oligosaccharides - Contains 3-6 sugar units Types of Carbohydrates  Functions: 1. Energy storage 2. Heat insulation 3. Membrane structure 4. Protection Lipids  -Composed of C,H,O,N and sulfur -Building blocks of Amino acids Proteins - Composed of C,H,O,P - Building blocks of nucleotides Nucleic Acid  1. DNA - Molecules of life - Found in the nucleus - 2 strand - Bases present: Adenine, Guinine, Thymine, Cytosine Types of Nucleic Acid  1. RNA - Found in the cytoplasm - 1 strand - Bases present: Adenine, Guinine, Uracil, Cytosine Types of Nucleic Acid CELLS - The basic unit of life. The Cell History of Cell Study 1. Anton Van Leeuwenhoek 2. Robert Hooke 3. Robert Brown 4. Matthias Schleiden and Theodore Schwann 5. Rudolf Virchow Types of Cells Prokaryotes Eukaryotes Cell structure Plant Structures Parts of the Plant Cell Cell Wall ✓An inert secretion, providing only strength and protection to the protoplasm inside. ✓It contains a considerable amount of cellulose ✓Microfibril – are adjacent, parallel cellulose molecules that crystallizes; it wound around the cell and completely covers the plasma membrane ✓Cellulose microfibrils are packed together by other polysaccharides called hemicelluloses, (produced in dictyosomes)  3 Layers of Cell Wall Primary Cell Wall Stretches and expands as the cell increases in size Middle Lamella A layer of pectic compounds Acts as a cement between the primary cell walls of adjacent cells Secondary Cell Wall Forms after growth ceases Forms between primary wall and the plasma membrane Contains cellulose and lignin Lignin (a hard substance that gives wood its distinctive texture) Parts of the Plant Cell Protoplasm It is a mass of proteins, lipids, nucleic acids and water within a cell Except for the wall everything in the cell is protoplasm. Parts of the Plant Cell Plasma Membrane aka plasmalemma Is the selectively permeable membrane that completely covers the surface of the protoplasm Molecular pumps keep substances moving by actively pumping them in and out of the cell. Parts of the Plant Cell Cytoplasm If the nucleus and vacuole are excluded from the protoplasm, the remaining material is the cytoplasm. Parts of the Plant Cell Mitochondrion (pl. mitochondria) Tiny organelles bounded by a double membrane Using Cellular Respiration “Powerhouse” of the cell  Crista (pl. cristae) – mitochondrial membranes are folded, forming large sheets or tubes which provides room for large number of enzymes Matrix – found between the cristae; place for reactions that do not involve highly reactive intermediates Outer mitochondrial membrane –freely permeable; gives shape and little rigidity to the mitochondrion. numerous pumps and channels. Inner mitochondrial membrane– selectively permeable membrane which forms the cristae. Center for ATP synthesis. Parts of the Plant Cell Parts of the Plant Cell Dictyosomes (Golgi Apparatus or Golgi Body) A stack of thin vesicles held together in a flat or curved array For growth and cell wall formation Cisterna (pl. cisternae) – ER vesicles accumulate on one side of dictyosome then fused together and form a wide, thin vesicle. Parts of the Plant Cell Endoplasmic Reticulum (ER) A system of narrow tubes and sheets of membrane that form a network throughout the cytoplasm Parts of the Plant Cell RER (Rough Endoplasmic Reticulum) – ER which contains ribosomes ; aids in protein synthesis SER (Smooth Endoplasmic Reticulum) – lacks ribosomes; for lipid synthesis and membrane assembly Parts of the Plant Cell Ribosomes Particles responsible for protein synthesis Complex aggregates of 3 molecules of RNA (ribosomal RNA) and about 50 types of proteins that associate to form 2 subunits Polysome – cluster of ribosomes that are bound together by messenger RNA Parts of the Plant Cell Microbodies Spherical bodies about 0.5 to 1.5μm in diameter 2 Classes: Both isolate reactions that either produce or use the dangerous compound peroxide (H2O2) Peroxisomes – involved in detoxifying by products of photosynthesis and found closely in chloroplasts Glyoxysomes – occur only in plants; converts stored fats to sugars; important in germination of fat-rich, oily seeds Parts of the Plant Cell Plastids Found in all plants and algae but never in animals, fungi or prokaryotes Group of dynamic organelles that perform many functions like: ✓Photosynthesis ✓Synthesis, storage and export of specialized lipid molecules ✓Storage of carbohydrates and iron ✓Formation of colors in some flowers and fruits ✓Each metabolism is associated with a particular type of plastid Parts of the Plant Cell Types of Plastid: Amyoplasts – store starch; considered to be leucoplast Chloroplasts – carry out photosynthesis; contains chlorophyll; A molecule with the vital role of absorbing light energy; Absorbs blue and red light (reflects green) Etioplasts – a specific stage in the transformation of proplastids to chloroplasts; occur when tissues are grown without light Proplastids – small, undifferentiated plastids Leucoplasts Colorless plastids form and store starches, oils, or proteins Common in seed, root, & stem cells Chromoplasts Contains yellow, orange, and red pigments Often form from chloroplasts when chlorophyll breaks down Ex: Tomatoes; deciduous tree leaves Parts of the Plant Cell Parts of Plastids: Inner and Outer Membrane Thylakoids – membrane sheets that projects to the stroma; folded in order to increase membrane area; provides more space for the insertion of photosynthetic pigments Granum (pl. grana) – the stack of baglike vesicles formed by thylakoids; essential in the transport of protons needed for photosynthesis Stroma – where conversion of carbon dioxide to carbohydrates occurs Parts of the Plant Cell Nucleus (pl. nuclei) Serves as an archive or permanent storage place for the plant’s genetic information Nuclear envelope – separates the nuclear material from the rest of the cell; it consists of nuclear pores that are involved in the transport of materials in the nucleus and the rest of the protoplasm Chromatin- darkly-staining bodies inside the nucleus. They contain genes.  Nucleoplasm – it is a complex association of : ✓DNA ✓Enzymes and other factors necessary to maintain, repair and read DNA ✓Histone proteins that support and interact with DNA (chromatin) ✓Several types of RNA ✓Water and other substances necessary for nuclear metabolism Parts of the Plant Cell Nucleolus (pl. nucleoli) Area where components of ribosomes are synthesized and partially assembled An organelle that contains DNA Serves as the control center of the cell Contains nucleoplasm DNA associates with certain protein molecules to form chromatin Chromatin strands coil and thicken during cell division to form chromosomes Parts of the Plant Cell Vacuole Appears to be an empty membrane which stores water and salts Sometimes contains visible crystals, starch, protein bodies and various types of granules and fibrous minerals Tonoplast – vacuole membrane Central vacuole – one large vacuole (as the cell grows and expands); functions as a storage for nutrients and waste products; digestive organelle Helps cell maintain turgid shape Provide strength for non-woody plants Temporary storage area for excess materials Parts of the Plant Cell Cytosol aka Hyaloplasm Volume of the cytoplasm which occurs as a clear substance composed of water, enzymes, and numerous chemical precursors, intermediates and products of enzymatic reactions Parts of the Plant Cell Microtubules Act as a “cytoskeleton”, holding certain regions of the cell surface back while other parts expand Assemble into arrays like an antenna Means of motility for both organelles and whole cells Framework that moves chromosomes during the division of nucleus Parts of the Plant Cell Types of Globular Proteins that Make up the Microtubules: Alpha tubulin Beta tubulin Centrioles – made up of 9 sets of 3 short microtubules; responsible for the organization and polymerization of the spindle microtubules Parts of the Plant Cell Microfilaments Are constructed in the assembly of globular proteins – just one type : actin Narrower than microtubules (3 to 6nm in diameter) Parts of the Plant Cell Hemicellulose – binds together cellulose microfibrils; produced from dictyosomes Lignin – together with hemicellulose, makes the 2° cell wall stronger; it has the ability to resist chemical, fungal and bacterial attack. Plasmodesmata – fine holes in the cell wall which interconnects plant cells Plant Cell vs. Animal Cell Plant Cell vs. Animal Cell Plant Cell Animal Cell Cell wall Present (formed of Absent cellulose) Shape Rectangular (fixed shape) Round (irregular shape) Vacuole One, large central vacuole One or taking up 90% of cell more small vacuoles volume. (much smaller than plant cells). Centrioles Only present in lower plant Present in all animal cells forms. Chloroplast Plant cells have Animal cells don't have chloroplasts because they chloroplasts make their own food Cytoplasm: Present Present Endoplasmic Present Present  Plant Cell vs. Animal Cell Plant Cell Animal Cell Ribosomes: Present Present Mitochondria: Present Present Plastids: Present Absent Golgi Apparatus: Present Present Plasma Membrane: cell wall and a cell membrane only cell membrane Microtubules/ Present Present Microfilaments: Flagella: May be found in some cells May be found in some cells Lysosomes: Lysosomes usually not Lysosomes occur in evident. cytoplasm. Nucleus: Present Present Cilia: It is very rare Present Plant Cell vs. Fungal Cell Cells of fungi are similar to plant cells with two important differences: ✓They do not contain plastids of any type ✓Their walls contain CHITIN, not cellulose except for some unusual group of fungi, the Oomycetes. *CHITIN - physically similar to cellulose, being tough, inflexible and insoluble in water, but it contains nitrogen and is synthesized in a different mechanism than that used for cellulose. Divisions of Kingdom Plantae Bryophyta – mosses Pteridophyta – ferns Coniferophyta – conifers Anthophyta – flowering plants 5 Kingdoms of Organisms Prokaryotes Kingdom Monera – bacteria and cyanobacteria Eukaryotes Kindom Protista – single-celled organisms (protozoans, algae); multicellular algae Kingdom Mycetae – fungi such as mushrooms, puffballs and bread mold Kingdom Animalia – animals Kingdom Plantae - plants Onion H. verticullata Staining of A. cepa roots